In recent years, attention has been given to hybrid vehicles and electric vehicles against the background of environmental issues. These vehicles is equipped with an electric motor as a drive power source, and is also equipped with a power storage device such as a secondary battery or a capacitor as an electric power supply thereof.
Generally, in the power storage device such as a secondary battery or a capacitor, when a temperature lowers, a capacitance lowers and thereby charge/discharge characteristics thereof lower. In the above kinds of vehicles, a temperature of the power storage device must be rapidly raised when the temperature of the power storage device is low after a vehicle system started.
Japanese Patent Laying-Open No. 2005-332777 has disclosed a warm-up control device that controls charge/discharge of a cold battery to warm up it by internal heat generation of the battery. This warm-up control device includes charge/discharge pattern setting means, limit value setting means and warm-up control means. Based on a battery state, charge/discharge pattern setting means variably sets a charge/discharge pattern in which the charging and discharging of the battery are alternately repeated in a pulse-like form. According to the battery temperature, the limit value setting means variably sets a limit value which limits a maximum amplitude of the charge/discharge pattern. According to the charge/discharge pattern that is set by the charge/discharge pattern setting means, the warm-up control means executes the charging and discharging of the battery without exceeding a range of the limit value set by the limit value setting means, when the battery temperature is lower than a defined temperature.
The above warm-up control device can efficiently control the charge/discharge according to the state of the battery when it is cold, and thereby can promote the temperature rise by the internal heat generation and quickly recover the battery capacity lowered when it is cold.
However, Japanese Patent Laying-Open No. 2005-332777 has not disclosed temperature rise control in a power supply system including a converter that is arranged between a battery and an inverter for voltage conversion between the battery and the inverter as well as and a power storage unit (e.g., a capacitor) connected, in parallel with the converter, to the inverter.